The coming executive actions to change immigration policy could become the defining moment in a second term marred by congressional gridlock. A mid fierce debate over the crisis along the U.S.-Mexico border they also could set up a potential political firestorm just weeks before the crucial midterm elections. Perhaps most importantly, Obama’s coming executive actions could also test the limits of presidential power.

“Depending on how far they go, yes,” David Martin, a professor at the University of Virginia School of Law who specializes in immigration law, told Business Insider. “It could be a significant challenge to the scope of presidential power.”

The White House has provided few hints on what Obama will do on immigration as a review by the Departments of Justice and Homeland Security on his options is still ongoing. The Washington Post has reported, based on readouts of meetings among White House officials, congressional Democrats, and activist groups, that Obama could effectively expand the Deferred Actions for Childhood Arrivals program. DACA, as it is known, has shielded hundreds of thousands of young undocumented immigrants brought to the U.S. as children from deportation .